What is gastric motility?
Peristaltic waves from the body of the stomach to the antrum (contractions)
How does contractions strength vary across the stomach?
Is different in different areas
What is the contraction strength like in the body of the stomach?
Weak because it has a thin muscle
What is the contraction strength like in the antrum of the stomach?
Powerful because has a thick muscle
Where in the stomach does mixing occur?
What happens when the pyloric sphincter is contracted?
Small quantitiy of gastric contents (chyme) enters the duodenum, further mixing occurs as antrul contents are forced back towards the body
What is gastric contents known as?
What is the gastric peristaltic wave produced by?
What is the peristaltic rhythm generated by?
Pacemaker cells in the longitudinal muscle layer
What is the rate of the peristaltic rhythm?
How does the signal from the peristaltic rhythm travel through the longitudinal muscle layer?
What must be reached for the stomach to contract?
Action potential must reach threshold
What is the slow wave rhythm of the peristaltic rhythm known as?
Basic electrical rhythm (BER)
What is the action potential size proportional to?
Tension on the stomach wall
Explain the hormonal/neural control of contractions?
Gastrin increases contraction
Distension of stomach wall causes long/short reflexes which increases contraction
Fat/acid/amino acid/hypertonicity in duodenum inhibits motility (contraction)
How does gastrin impact contraction?
How does distension of stomach wall impact contraction?
How does the presence of fat, acid, amino acid, or hypertonicity in the duodenum impact contraction?
What controls the force of contractions?
Frequency of action potentials
What secretes bicarbonate?
Brunner's glands duct cells
In what layer are Brunner's glands found?
What is neutralisation of acid in the duodenum done by?
What happens to the water and carbon dioxide produced during acid neutralisation?
Water flows down the gut and carbon dioxide diffuses away
Why is it important that the duodenum is not acidic?
It would denature enzymes from the pancreas and damage the duodenum epithelium which needs to absorb things such as iron
What does acid in the duodenum trigger?
Long (vagal) and short (ENS) reflexes causing HCO3 secretion
Release of secretin from S cells causing HCO3 secreiton
What are long reflexes controlled by?
What are short reflexes controlled by?
What does secretin cause?
Bicarbonate to be secreted from the pancreas and liver which will end up in the duodenum as well as from Brunner's glands in the duodenum
How does acid neutralisation impact secretin release?
Inhibitis secretin release (negative feedback control)
What are the 3 parts of the pancreas?
Head (located within curvature of duodenum)
Tail (extends to spleen)